Turkey on Friday widened the investigation into the disappearance of journalist Jamal Khashoggi after his visit to the Saudi consulate, searching a forest in the city.

Ankara also denied giving any audio recording to US officials from the investigation about Khashoggi, a former royal insider who moved to the United States after becoming a critic of the current House of Saud leadership.

Pro-government Turkish media have provided a steady stream of claims that Khashoggi was tortured and decapitated by a Saudi hit squad inside the consulate, although Ankara has yet to divulge details about the investigation.

Istanbul’s Belgrade forest became a target of the investigation after police focused on the vehicles which left the consulate on the day Khashoggi disappeared, NTV channel reported. At least one vehicle is suspected to have gone to the forest.

The forest, a vast area and sufficiently remote for even locals to regularly get lost there, is nearly 15km (nine miles) from the Saudi consulate.

Investigators already conducted two searches of the consulate and a nine-hour search of the consul’s residence this week. The Saudi consul, Mohammed al-Otaibi, abruptly left Istanbul for Riyadh on Tuesday.

Turkey’s state-run Anadolu news agency says prosecutors are questioning a number of employees of the consulate.

Private A Haber TV said as many as 15 employees were being questioned on Friday, including the consul’s driver, technicians, accountants and telephone operators.

Pro-government daily Sabah on Friday published new security camera images of some of the Saudi team arriving in Istanbul and reported that two of the men landed in the city on October 1.

Previously, local media said the 15 men arrived in Turkey on the day Khashoggi went missing via two private planes, which then returned to Riyadh via Egypt and Dubai.

Foreign Minister Mevlut Cavusoglu did not reveal more details but promised to share information in due course “in a transparent manner”.

“It is out of the question for us to share this or that information with any country,” he said during a visit to Albania’s capital, Tirana.

“Of course, as a result of the investigation so far, Turkey does have some information and evidence,” he said. “We will share them with the world when they become fully clear because the whole world, understandably, wants to know what happened to Khashoggi and how it happened.”

The key potential piece of evidence in the investigation is at least one alleged audio recording, the existence of which has been reported by pro-government media. They say the recordings prove Khashoggi was tortured and killed.

ABC News on Thursday quoted an unnamed Turkish official saying US Secretary of State Mike Pompeo heard the audio tape and was shown a transcript of the recording during his visit to Ankara.